FULLER QUOTATIONS FROM ' ZOONOMIA! 223 



extravagance, such as is likely to destroy the power 

 itself. Demand and Supply are also good illustrations. 



But to return to Dr. Darwin. 



" When we revolve in our minds," he writes, " first 

 the great changes which we see naturally produced in 

 animals after their nativity, as in the production of 

 the butterfly with painted wings from the crawling 

 caterpillar ; or of the respiring frog from the subnatant 

 tadpole; from the boy to the bearded man, from the 

 infant girl to the woman, in both which cases mutila- 

 tion will prevent due development. 



"Secondly, when we think over the great changes 

 introduced into various animals by artificial or acci- 

 dental cultivation, as in horses, which we have exer- 

 cised for the different purposes of strength or swiftness, 

 in carrying burthens or in running races, or in dogs 

 which have been cultivated for strength and courage, 

 as the bull-dog ; or for acuteness of his sense of smell, 

 as the hound or spaniel ; or for the swiftness of his foot, 

 as the greyhound ; or for his swimming in the water or 

 for drawing snow sledges, as the rough-haired dogs of 

 the north ; or, lastly, as a play dog for children, as the 

 lapdog ; with the changes of the forms of the cattle 

 which have been domesticated from the greatest anti- 

 quity, as camels and sheep, which have undergone so 

 total a transformation that we are now ignorant from 

 what species of wild animal they had their origin. Add 

 to these the great changes of shape and colour which 

 we daily see produced in smaller animals from our 

 domestication of them, as rabbits or pigeons, or from 

 the difference of climates and even of seasons ; thus the 



